1: <?php
 2: namespace Sotr\Crypto;
 3: 
 4: class CurrencyPair
 5: {
 6:     protected $currA;
 7:     protected $currB;
 8: 
 9:     public function __construct($currA, $currB)
10:     {
11:         $this->currA = strtolower($currA);
12:         $this->currB = strtolower($currB);
13:     }
14: 
15:     public function getCurrencies()
16:     {
17:         return [$this->currA, $this->currB];
18:     }
19: }
20: